A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such a case, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. including part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Conventional lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning”-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.
In order to accurately position the substrate and patterning device, positioning devices including electromagnetic actuators and linear motors are typically applied. As an example, such positioning device can comprise a planar motor or a linear motor assembly (such as an H-drive arrangement) for displacing the substrate (e.g. mounted to a support) over comparatively large distances and an actuator assembly comprising a plurality of electromagnetic actuators such as Lorentz actuators, for accurately positioning the substrate and support over comparatively small distances. Typically, such motors and/or actuators are optimized with respect to the generated force per unit electrical power. However, when demands with respect to acceleration are increasing, actuators thus optimized may itself become the limiting factor. Therefore, there is a need to review and redesign known actuators and supports for substrates or patterning devices, in order to address increasing demands with respect to acceleration, or in general, stage performance.